Somebody pointed out this fascinating teardown (sorry, can't remember who it was. Oops). It is a teardown of a 1986 Psion II organiser, a 1996 Palm Pilot 5000 (back when they were still US robotics and before Pilot pens made them drop the Pilot name) and then an HP iPaq 5550. It is interesting to watch the level of integration increase and the density of the circuit boards really go down as IC packaging technology changes (these are all QFP chips I think). It is amazing how much stuff we integrate on to a modern SoC rather than requiring separate backup chips.